I have received these, as well. I reported them to my state police and state attorney general, who followed up and told me that they had been trying to go after these guys for some time.  I told the caller that the company he was claiming I owed to told me that they were not authorized by them and that they'd never even heard of them.  They quit calling for a while, then started up again! I block them from my phone.  Even when they call back from another number, I remove their old number and block the new one. Hopefully, they get the hint.